Editing Magnetohydrodynamics (section)

== Structures in MHD systems ==
{{Further|Magnetosphere particle motion}}
[[File:Currents.jpg|right|thumb|250px|Schematic view of the different current systems which shape the Earth's magnetosphere]]

In many MHD systems most of the electric current is compressed into thin nearly-two-dimensional ribbons termed [[current sheet]]s.<ref>{{cite journal | doi=10.1007/s41116-022-00032-9 | title=Magnetic reconnection: MHD theory and modelling | year=2022 | last1=Pontin | first1=David I. | last2=Priest | first2=Eric R. | journal=Living Reviews in Solar Physics | volume=19 | issue=1 | page=1 | bibcode=2022LRSP...19....1P | s2cid=248673571 | doi-access=free }}</ref> These can divide the fluid into magnetic domains, inside of which the currents are relatively weak. Current sheets in
the solar corona are thought to be between a few meters and a few kilometers in thickness, which is quite thin compared to the magnetic domains (which are thousands to hundreds of thousands of kilometers across).<ref>{{cite journal | url=https://link.springer.com/article/10.1007/s11214-021-00814-x | doi=10.1007/s11214-021-00814-x | title=Current Sheets, Plasmoids and Flux Ropes in the Heliosphere | year=2021 | last1=Khabarova | first1=O. | last2=Malandraki | first2=O. | last3=Malova | first3=H. | last4=Kislov | first4=R. | last5=Greco | first5=A. | last6=Bruno | first6=R. | last7=Pezzi | first7=O. | last8=Servidio | first8=S. | last9=Li | first9=Gang | last10=Matthaeus | first10=W. | last11=Le Roux | first11=J. | last12=Engelbrecht | first12=N. E. | last13=Pecora | first13=F. | last14=Zelenyi | first14=L. | last15=Obridko | first15=V. | last16=Kuznetsov | first16=V. | journal=Space Science Reviews | volume=217 | issue=3 | s2cid=231592434 }}</ref> Another example is in the Earth's [[magnetosphere]], where current sheets separate topologically distinct domains, isolating most of the Earth's [[ionosphere]] from the [[solar wind]].